Renal hemodynamic and glomerular permselectivity studies of early diabetes mellitus will be the subjects of this research in an effort to elucidate the basis for the albuminuria associated with experimental diabetes mellitus. We propose to study the selective renal clearance of selectivity charged dextran molecules as well as the functional filtration properties of the diabetic kidney. Using quantitative stereologic techniques we will describe the morphologic equivalents of the glomerular filter and will relate the onset and course of albuminuria to the morphologic appearance of lysozyme in the glomerular filter. By superimposing diabetes mellitus upon the kidney of the spontaneously hypertensive rat and in the model of unilateral nephrectomy, we will be abe to dissect the pressure flow and resistance relations in conjunction with the histochemical and quantitative morphometric approaches to studying the mechanisms leading to altered glomerular permeability in diabetes mellitus.